NCERT Solutions for Class 4th Maths Chapter 12 Observe the shaded portions — In-text Questions
Book page 182 Updated on2026-09-19
Q1.
Akira has spent one hour from 8:00 AM to 9:00 AM. / No, she has spent 60 minutes. Who do you think is correct? Is there any relation between 1 hour and 60 minutes?
Answer
What the two girls say about the time from 8:00 AM to 9:00 AM.
Both girls are correct. They are saying the same thing in two different ways.
1 hour = 60 minutes
8:00 AM
9:00 AM
From 8:00 to 9:00 the long hand goes once all the way round the face.
From 8:00 AM to 9:00 AM the short hand moves from 8 to 9 — that is 1 hour. In the same time the long hand goes once all the way round and crosses all 60 small marks — that is 60 minutes.
Why it happens: The clock face has 60 small marks in one full round. The long hand crosses one mark every minute, so one full round is 60 minutes, and one full round is exactly the time the short hand needs to move from one number to the next.
Tip: So you may say “one hour” or “60 minutes” — both are right.
Q2.
Observe the shaded portions. One hour (1 hour) = 60 minutes. Half hour = ____ minutes. Quarter or 1/4 of an hour = 15 minutes. Three Quarters or 3/4 of an hour = ____ minutes.
Answer
One hour (1 hour) = 60 minutes
Half hour = ____ minutes
Quarter or 1/4 of an hour = 15 minutes
Three Quarters or 3/4 of an hour = ____ minutes
The four shaded clock faces printed on page 182.
The whole face is 60 minutes. Share those 60 minutes into equal parts.
Half hour: 60 in 2 equal parts → 30 + 30 = 60 → Half hour = 30 minutes Quarter hour: 60 in 4 equal parts → 15 + 15 + 15 + 15 = 60 → one part = 15 minutes Three quarters: 15 + 15 + 15 = 45 minutes
One hour = 60 minutes
Half hour = 30 minutes
Quarter hour = 15 minutes
Three quarters = 45 minutes
The same four faces with both blanks filled in.
So half an hour = 30 minutes and three quarters of an hour = 45 minutes.
Why it happens: The shaded part of the second clock is exactly half the face, and half of 60 is 30. The fourth clock is shaded from 12 right round to 9, which is three of the four quarters.
Check it yourself: 30 + 15 = 45, and 45 + 15 = 60. The quarters fit together to make the whole hour.